This invention relates to instrument panels incorporating a vacuum fluorescent (VF) display, and more particularly to illumination of instrument panel indicia by the VF display.
Vacuum fluorescent (VF) displays are generally manufactured in the form of a glass housing having an evacuated central cavity containing phosphored anode segments arranged in a suitable display pattern, and a grid disposed between the anode segments and a filament (cathode). The filament is electrically heated to generate a cloud of electrons, which are attracted by the grid and driven into the phosphored anode segments, resulting in emission of light at the phosphor surface. The emitted light is very bright, but is usually extensively filtered so that a viewer of the panel only sees the illuminated anode segments. Frequently, the instrument panel is also provided with separate light sources for illumination of other indicia formed on the panel. In an automotive radio or HVAC control panel, for example, a VF display is used to communicate certain parameters to the operator, and various incandescent light sources are used to illuminate legends or other indicia on adjacent control knobs or buttons. The indicia light source and associated light-piping can significantly increase the size, complexity and cost of the display panel, and a considerable effort is typically entailed in matching the color of the indicia illumination with that of the display illumination. Accordingly, what is needed is a way of using light from the VF display to illuminate other indicia of the instrument panel.
The present invention is directed to an improved display panel including a VF display having an integral VF light source that is shielded from viewer of the display, and that provides illumination for display panel indicia formed in the vicinity of the VF display. According to the invention, the integral light source for indicia illumination is produced at marginal areas of the VF display by one or more secondary anode segments and associated reflector structures that direct the light produced by the secondary anode segments laterally through a transparent side glass of the display housing. A light-pipe structure adjacent the VF display receives the laterally directed light, and uses the received light to backlight the panel indicia.